Fully enclosed switching devices for high voltages



Dec. 23. 1969 R; BOERSMA ET AL 3,485,971

FULLY ENCLOSED SWITCHING DEVICES FOR HIGH VOLTAGES Filed June 17, 1968 PIC-3.21

IN VENTORS RINTJ'E BoERSMA GIJ'SBERT W. IRi BY ATTORNEYS United States Patent M a 485 971 FULLY ENCLOSED swlircmNo DEVICES non HIGH VOLTAGES Rintje Boersma, Harmelen, and Gijsbert W. Irik, Bilthoven, Netherlands, assignors to N.V. COD, Utrecht,

US. Cl. 200-48 4 Claims ABSTRACT OF THE DISCLOSURE Two end sections of a metal envelope enclosing a switching device are detachably connected to an intermediate section. The end sections house stationary switch contacts connected to conductors across which a high voltage may be impressed. The intermediate section is provided with a transverse insulating wall separating the interior of the envelope into isolated chambers and mounting an isolating switch having movable contacts normally engaged with the stationary contacts to complete the circuit. The envelope is grounded and the intermediate section is provided With a switch for grounding the movable contacts when they are out of contact with the stationary contacts.

The invention relates to a fully enclosed switching device for high voltages, comprising a metal casing to be connected to earth potential and containing switching sections each provided with at least two elements con nected to each other by means of an isolating switch, said isolating switch being provided with two stationary contacts spaced apart and each permanently connected to one of said elements, a double acting, two-part movable switching contact carried by a stationary transverse wall made of insulating material and an earth contact electrically connected to said casing, said movable switching contact being movable such as to bring its one part into contact with or to separate said one part from one of said stationary main contacts and to bring its other part into contact with or to separate said other part from the other one of said stationary main contacts, which movable switching contact, furthermore, may be conductively connected to said metal casing by said earth contact in the switched-off position of the device, said transverse wall dividing the space inside said metal casing permanently into two separated compartments each containing at least a part of one of said elements together with the stationary main contact permanently connected thereto and with the movable switching contact part cooperating with said stationary main contact.

Switching devices .of this type are known from the British patent specification 472,656. The transverse wall of insulating material and the earth contact permit spatial and electrical division of the two elements separated by the isolating switch so that, without any danger, work on the one element may be carried out with the other element under voltage. In this known switching device the insulating transverse wall is clamped directly between the flanges of the two flange-connected portions of the casing which contains the elements to be electrically connected to each other. This construction renders it impossible to remove the one portion of the casing together with the elements and members contained therein without the transverse wall together with the movable part of the isolating switch being removed and without the other casing portion with its elements and members it comprises being opened thereby as well. The known Patented Dec. 23, 1969 device, therefore, has the disadvantage that removal of one portion of the switching device parts to be connected by the isolating switch renders it necessary that the other portion of the device as well as the part thereof to be removed is switched off from the voltage which in many cases implies that the bus bar systems and hence the complete device must be de-energized.

The invention aims at eliminating this disadvantage of the known switching device. The invention prescribes that the transverse wall made of insulating material and the double acting, two-part, movable switching contact carried thereby are supported by and mounted within a portion of said metal casing, said casing portion furthermore supporting said earth contact and, at and adjacent both sides of said transverse wall, being separably connected to casing portions each containing one stationary main contact of said switching device and an element or part of an element permanently connected to said .one stationary main contact.

Should one of both casing portions together with the elements and members contained therein be removed, then the transverse wall remains secured to the other portion as a cover. This is especially of importance when the compartments of the switching device are filled with a gas under pressure, f.i. sulphur hexafluoride (SP and the condition of insulation of the device is strongly dependent on the gas pressure. If in that case the one portion of the switching device is removed, the other portion may be kept under normal gas pressure and may hence safely remain under voltage.

In order to allow inspection, repairs or replacement of the parts of the double acting, two-part, movable switching contact of the isolating switch and cleaning of the insulating transverse wall as well, a construction is preferred in which each of the parts of said double acting, two-part, movable switching contact of said isolating switch is separably and removably connected to the actuating mechanism as Well as to the other one of said parts. After the isolating switch has been switched off and the one casing portion with contents has been removed that part of the movable switching contact which is located at the exposed side of the insulating transverse wall may also be removed.

If the switching device is so constructed that the plans of division between said portions of the metal casing extend in directions transverse to the longitudinal axes of the free spaces between the switched-off parts of the movable switching contact and the stationary main contacts of the isolating switch cooperating therewith then the casing portion comprising the transverse wall and the switched-01f double switching contact can be removed in transverse direction from the device the casing portion comprising the stationary isolating switch contacts and the elements permanently connected thereto remain in place. It is clear that these stationary contacts and these elements are to be cut off from the voltage.

The invention will be elucidated with reference to the accompanying drawing. In the drawing:

FIG. 1 shows an axial section through two parts of a switching device according to the invention said parts being connected to each other by an isolating switch having axially movable switching pins and FIG. 2 shows a vertical section through a switching section of such a switching device having isolating switches and corresponding principally to the device of FIGURE 1.

The device of FIG. 1 consists of two portions 1 and 2 of a fully enclosed switching device, the conducting elements (not-shown in the drawings) of which such as a bus bar or a bus bar system, a power switch, cable connectors or similar parts are mounted in separate compartments of the metal casing of the device and may be electrically connected to each other by means of an isolating switch 3. The casing of this isolating switch consists of four coaxial tube-shaped portions 4, 5, 6 and 7, respectively, of which the portions 4 and 7 are secured to the parts 1 and 2 respectively, of the switching device and are surrounded by stationary main contacts 10, 11 supported by bushing insulators 8, 9, respectively. These stationary main contacts are permanently connected to the aforementioned elements to be connected by the isolating switch by means of connectors 12, 13. The tubeshaped intermediate portion situated between portions 4 and 7 of the casing consists of two portions 5 and 6 connected by means of flanges 14, 15, to flanges 16, 17 of casing portions 4, 7, respectively,'as well as connected to each other by means of flanges 18, 19. Between the flanges 18, 19 a transverse wall 20 of insulating material is clamped which simultaneously supports driven, axially movable switching rods 21 and 22. Each switching rod 21 (22) is provided with a rack bar 23 (24) engaging a gear wheel 26 mounted on a drive shaft 25. This drive shaft may be actuated from outside by means of an insulated part (not shown). The axially movable switching rods 21, 22 cooperate with the stationary main contacts and 11, respectively, and are permanently conductively connected to each other in a way not shown. The switching rods 21, 22 are each screwed to an axial screw threaded pin 27 secured to the rack bars 23, 24 so as to be easily dismounted, repaired or replaced. Rack bar 23 of switching rod 21 is permanently electrically connected to a stationary auxiliary contact 28 situated in the transverse Wall 20, an earth contact 29 constructed as an axially movable switching rod cooperating with the auxiliary contact 28. This earth contact is moved by a piston 31 slidably mounted in a cylinder 30. During the switch-off operation the movement control of the earth contact is effected in such a way (not represented in the drawing) as to be moved into its active position only after switching rods 21, 22 have been moved over sufficient distance from the stationary main contacts 10, 11, respectively.

If, for example, portion 1 of the switching device has to be removed from the device for maintenance or other purposes, flanges 14 and 16 are to be disconnected. The transverse wall 20, together with the then obviously switched-off and earthed switching rods 21 and 22, in that case remains in place so that the stationary main contact 11 situated in the, e.g. gas filled, compartment 32 and that element in portion 2 of the switching device, which is permanently connected thereto, may remain under voltage. Furthermore, switching rod 21 and the transverse Wall surface facing this rod may be inspected, repaired or cleaned. If the portion 2 of the switching device has to be removed or if the other side of the insulating switch has to be inspected, flanges and 17 have to be disconnected and stationary main contact 10 together with the switching device parts connected thereto may remain under voltage.

It appears from FIG. 1 that planes of division 33, 34 between flanges 14, 16 and 15, 17, respectively, intersect the free spaces between the switched-off switching rods 21, 22 and the stationary main contacts. This enables after the complete switching device has been de-energized, removal of intermediate casing portion 5, 6 together with transverse wall and switching rods 21, 22 as a whole from the switching device in the transverse direction thereof, whereas the portions 1 and 2 together with the shaft portions 4 and 7, the bushing insulators 8 and 9, the stationary main contacts 10 and 11, connecting conductors 12 and 13 and the elements in portions 1 and 2 permanently connected thereto remain in place.

It should be remarked that intermediated portion 5, 6 of the metal casing of the isolating switch may also consist of a single tube into which the transverse wall 20 is slid and within which it is kept in place by inner flanges. Such a construction is shown in FIG. 2.

FIG. 2 shows a one-phase switching section of a fully enclosed switching device comprising two bus bar systems 35, 36, two bus bar isolating switches 37, 38 constructed approximately in a way similar to that of FIG. 1, the intermediate portion and the insulating transverse wall and the switching rods of these isolating switches consisting of one piece 39, 40, respectively. The switching device, furthermore, comprises a power switch 41, a cable insulating switch 42 similar to bus bar isolating switches 37, 38 and provided with an intermediate portion 43, and a cable terminating box 44. The switching device is a special one in that intermediate portions 39, 40 of each bus bar isolating switch 37, 38 are separably and removably arranged between connecting stubs 45, 46 of metal tubes 47, 48 surrounding bus bars 35, 36, respectivley, and connecting stubs 49, 50, respectively, of metal vessel 51 of power switch 41 and in that intermediate portion 43 of cable isolating switch 42 is separably and removably arranged between a connecting stub 52 of vessel 51 and a connecting stub 53 of a metal housing 54 of cable terminating box 44. In this switching device the halves of separating switches 37, 38, 42 are not mounted in separate compartments of the device. The spatial and electrical separation of the bus bar systems on the one hand and of the power switch on the other, that of the power switch on the one hand and of the cable terminating box on the other by means of the insulating transverse wall, as well as that of the intermediate portions-together with their transverse walls and switching rods, of the isolating switches of the power switch, of the bus bar systems and of the cable terminating box render in many cases the use of such individual compartments superfluous. Thus a considerable simplification of the construction is obtained and considerable space is saved because the bushing insulators for connection of the stationary main contacts of the isolating switches to the other elements of the switching device have been suppressed.

What we claim is:

1. A fully enclosed switching device for high voltages, comprising a metal casing to be connected to earth potential and containing switching sections each provided with at least two elements connected to each other by means of an isolating switch, said isolating switch being provided with two stationary contacts spaced apart and each permanently connected to one of said elements, a double acting, two-part movable switching contact carried by a stationary transverse wall made of insulating material and an earth contact electrically connected to said casing, said movable switching contact being movable such as to bring its one part into contact with or to separate said one part from one of said stationary main contacts and to bring its other part into contact with or to separate said other part from the other one of said stationary main contacts, which movable switching contact, furthermore, may be conductively connected to said metal casing by said earth contact in the switched-off position of the device, said transverse wall dividing the space inside said metal casing permanently into two separated compartments each containing at least a part of one of said elements together with the stationary main contact permanently connected thereto and with the movable switching contact part cooperating with said stationary main contact, characterized in that the transverse wall made of insulating material and the double acting, two-part, movable switching contact carried thereby are supported by and mounted within a portion of said metal casing, said casing portion furthermore supporting said earth contact and, at and adjacent both sides of said transverse wall, being separably connected to casing portions each containing one stationary main contact of said switching device and an element or part of an element permanently connected to said one stationary main contact.

2. Fully enclosed switching device according to claim 1, characterized in that each of the parts of said double acting, two-part, movable switching contact of said isolating switch is separably and removably connected to the actuating mechanism as well as to the other one of said parts.

3. Fully enclosed switching device according to claim 1 characterized in that the plans of division between said portions of the metal casing extend in directions transverse to the longitudinal axes of the free spaces between the switched-off parts of the movable switching contact and the stationary main contacts of the isolating switch cooperating therewith.

4. Fully enclosedswitching device according to claim 2 characterized in that the plans of division between said portions of the metal casing extend in directions transthe switched-off parts of the movable switching contact and the stationary main contacts of the isolating switch cooperating therewith.

References Cited UNITED STATES PATENTS 4/1961 Friedrich 200l45 X 3/1964 Waterton 200145 X 10 ROBERT K. SCHAFER, Primary Examiner verse to the longitudinal axes of the free spaces between 15 200 145, 163

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 485, 971 Dated December 23, 1969 Inventor(s) Rintje Boersma and Gijsbert Waldemar Irik It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the notice of assignee "N.V. COD" should read "N.V. COQ".

SIGNED AND SEALED JuL14197D 68m Am Edward M. Fletcher, Ir. mm 1: sum .m Anestin Offi r Gomissioner 01 Patent: 

